High-energy hadronic collisions generate environments characterized by temperatures above 100 MeV (refs. ^1,2 ), about 100,000 times hotter than the centre of the Sun. At present, it is therefore unclear how light (anti)nuclei with mass number A of a few units, such as the deuteron, ³ He or ⁴ He, each bound by only a few MeV, can emerge from these collisions ^3,4 . Here, the ALICE Collaboration reports that deuteron–pion momentum correlations in proton–proton (pp) collisions provide model-independent evidence that about 90% of the observed (anti)deuterons are produced in nuclear reactions ⁵ following the decay of short-lived resonances, such as the Δ(1232). These findings, obtained by the ALICE Collaboration at the Large Hadron Collider, resolve a gap in our understanding of nucleosynthesis in ultrarelativistic hadronic collisions. Apart from offering insights on how (anti)nuclei are formed in hadronic collisions, the results can be used in the modelling of the production of light and heavy nuclei in cosmic rays ⁶ and dark-matter decays ^7,8 .

We investigate the finite-size effects on the transition temperature associated with the quark-gluon plasma (QGP) formation. From a percolation perspective, the onset of the QGP in high-energy collisions occurs when the spanning cluster of color strings emerges. The principal result presented here is the finite-size effects on the transition temperature expressed as a power law in terms of the nucleon number. We found that the transition temperature is higher for small systems than for large ones. It means that minimal triggering conditions events in pp collisions require about 20 times higher energies than AuAu-PbPb collisions. We also estimate the center-of-mass energy required for the QGP formation as a function of the nucleon number. Our results are consistent with the minimal center-of-mass energies at which the QGP has been observed.

We investigate the transverse momentum distribution (TMD) statistics from three different theoretical approaches. In particular, we explore the framework used for string models, wherein the particle production is given by the Schwinger mechanism. The thermal distribution arises from the Gaussian fluctuations of the string tension. The hard part of the TMD can be reproduced by considering heavy tailed string tension fluctuations, for instance, the Tsallis $q$-Gaussian function, giving rise to a confluent hypergeometric function that fits the entire experimental TMD data. We also discuss the QCD-based Hagerdon function, another family of fitting functions frequently used to describe the spectrum. We analyze the experimental data of minimum bias $pp$ collisions reported by the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) experiments (from $\sqrt{s}=0.2$ TeV to $\sqrt{s}=13$ TeV). We extracted the corresponding temperature by studying the behavior of the spectra at low transverse momentum values. For the three approaches, we compute all moments, highlighting the average, variance, and kurtosis. Finally, we compute the Shannon entropy and the heat capacity through the entropy derivative with respect to the temperature. We found that the $q$-Gaussian string tension fluctuations lead to a monotonically increasing heat capacity as a function of the center-of-mass energy, which is also observed for the Hagedorn fitting function. This behavior is consistent with the experimental observation that the temperature slowly rises with increments of the collision energy.

In color string models, the transverse momentum distribution (TMD) is obtained through the convolution of the Schwinger mechanism with the string tension fluctuations distribution. Considering aq-Gaussian distribution for these fluctuations, the TMD becomes a hypergeometric confluent function that adequately reproduces the characteristic scales at low and highp_Tvalues. In this approach, the hard scale of the TMD is a consequence of considering a heavy-tailed distribution for the string tension fluctuations whose width rises as s , multiplicity or centrality increases. In this paper, we introduce broader information of the TMD in the color string percolation model by determining the color suppression factor, which now also depends on the parameters of theq-Gaussian. To this end, we analyze the reported data on pp and AA collisions at different center of mass energies, multiplicities, and centralities. In particular, for minimum bias pp collisions, we found that theq-Gaussian parameters and the effective temperature are monotonically increasing functions of the center of mass energy. Similar results are found for AA collisions as a function of the centrality at fixed s . We summarize these results in a phase diagram that indicates theq-Gaussian parameters region allowing the quark–gluon plasma formation.

The interaction between pions and nucleons plays a crucial role in hadron physics. It represents a fundamental building block of the low-energy QCD dynamics and is subject to several resonance excitations. This work studies the $$\text {p--}\uppi ^{\pm }$$ p-- π ± dynamics using femtoscopic correlations in high-multiplicity pp collisions at $$\sqrt{s} = 13$$ s = 13 TeV measured by ALICE at the LHC. As the final-state interaction between protons and pions is well constrained by scattering experiments and the study of pionic hydrogen, the results give access to information on the particle-emitting source in pp collisions using the femtoscopy methods. The scaling of the source size of primordial protons and pions against their pair transverse mass is extracted. The results are compared with the source sizes studied with p–p, $$\text {p--K}^+$$ p--K + , and $$\uppi ^\pm $$ π ± – $$\uppi ^\pm $$ π ± pairs by ALICE in the same collision system and are found to be in agreement for the different particle pairs. This reinforces recent findings by ALICE of a common emission source for all hadron-pairs in pp collisions at LHC energies. Furthermore, the $$\text {p--p--}\uppi ^{\pm }$$ p--p-- π ± systems are studied using three-particle femtoscopy in pp collisions at $$\sqrt{s} = 13$$ s = 13 TeV. The presence of three-body effects is analyzed utilizing the cumulant expansion method. In this formalism, the known two-body interactions are subtracted in order to isolate the three-body effects. For both, $$\text {p--p--}\uppi ^{+}$$ p--p-- π + and $$\text {p--p--}\uppi ^{-}$$ p--p-- π - , a non-zero cumulant is found, indicating effects beyond pairwise interactions. These results give information on the coupling of the pion to multiple nucleons.

A signal consistent with the $\mathrm{\ensuremath{\Omega}}(2012)$ baryon has been observed with a significance of $15\ensuremath{\sigma}$ in pp collisions at $\sqrt{s}=13\text{ }\text{ }\mathrm{TeV}$ at the LHC. In this paper, the analysis technique is described and measurements of the mass and width of the $\mathrm{\ensuremath{\Omega}}(2012)$ are reported, along with the first measurement of its transverse-momentum spectrum and yield. This paper corroborates the observation by the Belle Collaboration of this excited $\mathrm{\ensuremath{\Omega}}$ state and the observation that the $\mathrm{\ensuremath{\Omega}}(2012)$ has a rather narrow width for a strongly decaying resonance. The yield measurement is combined with a statistical thermal model calculation of strange baryon yield ratios to obtain estimates of the $\mathrm{\ensuremath{\Omega}}(2012{)}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Xi}}\overline{\mathrm{K}}$ branching ratios. These results will improve our understanding of the internal structure and mass spectrum of excited baryon states and serve as a baseline for searches regarding modifications of these properties in high-temperature media.